of berlin



Patented Feb. 3, 1931 UNITED" STATES PATENT OFFICE GEORG E A. RICHTER AND MILTON O. SCHUR, 0F BERLIN, NEW HAMPSHIRE, ASSIGNORS 'IO BROWN COMPANY, OF BERLIN, NEW HAMPSHIRE, A CORPORATION OF MAINE FIBER-LIBERATING PROCESS No Drawing.

This invention involves the liberation of fiber from raw cellulosic materials, particularly woods of high resin content such-as heretofore considered inferior raw material for the production of pulp.

In producing pulp from woods of resinous character, alkaline processes of digestion have generally been found more satisfactory than the sulphite process, as the alkali reacts with and dissolves not only the ligneous components of the wood but also a certain amount of the resinous components. There are certain woods so rich in resin, however, that even alkaline digestion does not produce a pulp of suitable quality, the resin content being sufiiciently reacted upon and removed by the alkali. This doubtless may be ascribed to the fact that the resin content of wood I comprises resins both of a saponifiable character and inert resins, perhaps of the nature of polymerized hydrocarbons which survive alkaline digestion and are present in considerable quantity in the resulting pulp. Such residual resins when present in a pulp tend to clog and gum washing cylinders and thickeners and raise havoc withthe wiresv and felts of papermaking machinery, so that woods rich in resin, such as jack pine, although found in abundance, have been employed only to a limited extent for the production of pulp.

We have found that if soap is present in the usual alkaline digesting liquors, the difiiculties heretofore encountered when woods of even a highly resinous character are employed as a raw material are largely eliminated, and a softer pulp having good papermaking qualities produced. While we are unable to account precisely for these results, it is quite likely that the soap component of the digesting liquor disperses or colloidally dissolves unsaponifiable or diflicultly saponifiable resins which the alkali cannot react with and dissolve.

A procedure such as described permits the use of soap-formin substance rather than previously prepare soap, as soap may be readily produced in situ in the digester while digestion is taking place. Furthermore, the action of the soap upon the resins facilitates 1927. Serial No. 201,957.

the resolution of the chips into fiber. The soaps which we employ may be straightchain, fatty acid soaps such as sodium oleate, sodium palmitate or sodium stearate, or ringstructure soaps such as rosin soap or the soaps of sulphonated oils. As soap-forming substance, we may employ oils orfats such as palm oil, coconut oil, peanut oil, or other fatty acid glycerides or fatty acids which would saponi-fy readily under the conditions prevailing during digestion to produce soap.

In practising the process of the present invention, we may proceed along the same general lines followed when practising usual alkaline digestion, but the wood employed as raw material may be of a resinous or highly resinous character, such as jack pine. The wood is chipped and then charged into a dige'ster of the usual type employed for alkaline digestion, whereupon the alkaline liquor desired is run into the digester. I The liquor may be the so-called sulphate liquor consisting essentially of a solution of caustic soda and sodium sulphide, or the so-called soda liquor consisting essentially of a solution of caustic soda. only. To the liquor is then added sufiicient soap or soap solution to produce a soap concentration of 0.3% to 0.4%, basedon liquor. The soap concentration may be varied, however, depending upon the resin ontent of the particular wood employed as a raw material, and the extentto which it is desired to deresinify the pulp. Inlieu of,

adding a prepared soap, we may add soapforming substance, such as palm oil, in

amount sufficient to produce the desired soap concentration, and when this is done, the

caustic soda content of the liquor is preferably s ufliciently in excess of the usual content to allow forthe saponification of such soa forming substance. gested under pressure and atelevated temperature until a fiber liberation has been effected, as is customary inalkaline digestion. During digestion, the alkali exerts its usual function of dissolvingthe encrusting material from the wood and at the same time the soap reacts upon and disperses resins -which are not reacted on by the alkali and which otherwise would be present in the re- The charge is then isulting pulp. If soap-forming substance has beenadded, saponification of such substance takes place quite readily as digestion proceeds, producin soap in situ and effecting the desired deresinlfication of the pulp. The

soap greatly assists the alkali in softening the fiber and in promoting a fiber liberation from the chips. It also effects a detergent effect upon the smaller non-resinous particles usually present in pulp, particularly alkalinedigested pulp, and enhances the bleacha'bility of such pulp.

'After digestion, the pulp maybe separated from the spent liquor, is by passing such pulp through a washer as usual. Inasmuch as the pulp has been deresinified during digestion,

no difliculty is experienced due to gumming of the washingcylinders; nor does such pulp do mischief to thickeners or papermaking machinery with which it subsequently contacts.

The separated spent liquor may be subjected to recovery processing such as usually practised in connection with alkaline digestion. The spent liquor is of higher organic or combustible content than usual, owing to the removal of resins from .the wood and the fatty acid grouping of the soap, and hence when concentrated and incinerated in a combined boiler-smelter furnace for the recovery of its valuable sodium constituent gives a higher fuel value. ordinarily. The recovery of sodium constituent previously present in the digesting liquor in the form of soap and fiber-liberating chemical may thus be effected in 'one operation.

When a highly resinous wood such as jack pine is employed raw material, peptizing agents such as sodium phosphate, borax, talc, or colloidal 018K may be employed to good advantage in t e digesting liquor, together with the soap, to assist in deresinifyin the pulp.

I3y the process of the present invention, woods of high resin content may be converted into pulp satisfactory for papermak- .ess. is practically the same as that necessary 1 in usual alkaline digestion, and the valuable sodium constituent of the soap may be 'recovered alon with the sodium constituent of the fiber-liberating chemicals. Furthermore, deresinification is accomplished under ve'ri'y favorable conditions, as under the influence of heat and pressure such as pre- Vailsduring; digestion, the resin mmtent is believed to exist in a softened or plastic condition, permitting very efiective action by the soap. 4

Having thus described our invention, it is evident to those skilled in the art that vari ous changes might be resorted to without departing from its spirit or scope as defined in the appended claims.

What we claim is 1. A fiber-liberating process which comprises digesting chipped wood under pressure and at elevated temperature in an alkaline liquor of a saponaceous character.

2. A fiber-liberating process which comprises digesting chipped wood under pressure and at elevated temperature in an alkaline liquor containing soap and a peptizing agent.

3. A fiber-liberating process which comprises digesting chipped jack pine under pressure and at elevated temperature in an alkaline liquor containing soap.

4. A process which comprises digesting a resinous wood underlpressure-and at elevated temperature in an al soap, separating the spent liquor from the resulting pulp, and recovering the sodium constituent from the spent liquor. 5. A fiber-liberating process which comprises digesting chipped woodin an alkaline liquor containing about 0.3% to 0.4% soap, based on liquor. 6. A fiber-liberating process which comprises digesting wood under pressure and at elevated temperature in an alkaline liquor containing a soap-forming substance and sufiicient caustic soda to sa nify such substance and to eflecta liberatlon of fiber from such wood. v

7. A fiber-liberating recess which comprises digesting chippe wood under pressure and at elevated temperature in an alkaline liquor containing a fatty acid glycende and suflicient caustic soda to saponify the glyceride and effect a liberation of fiber from such wood.

In testimony whereofwe have aflixed our signatures,

' GEORGE'A. RICHTER.

MILTON O. SCHUR.

v aline liquid containing sodium base compounds and a SOdlllIIl base 

